Although progress has been made in the treatment of certain types of leukemia, elucidation of the pathophysiology of this group of disorders has been hampered at least in part because of our limited ability to characterize abnormally proliferating cells at the biochemical level. Leukemic cells have traditionally been categorized based on appearance, staining characteristics and certain immunologic markers. Monoclonal antibodies have recently emerged as a useful tool for cell typing. At the same time, it has become possible to resolve hundreds of proteins by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Important limitations of the technique have been overcome with the availability of equipment that allows simultaneous analysis of large numbers of samples and the recent description of extremely sensitive silver staining techniques that do not require isotopic labeling and autoradiography for the visualization of protein spots in gels. The aim of the proposed research is to take advantage of the resolving power of 2-D PAGE and high pressure liquid chromatography (HPLC) to undertake a systematic search for differences in the polypeptide composition of leukemic cells obtained from children with various types of acute leukemia. The proposed research will be carried out as a regional study involving several centers that are part of the Children's Cancer Study Group. The plan is to analyze by 2-D PAGE leukemic cells obtained at the time of initial diagnosis and subequent relapse from children with acute lymphocytic and non-lymphocytic leukemia. The extent of variability in the protein patterns of different individuals will be determined by cytocomputer image analysis. The variability observed will be related to the morphological, histochemical, immunologic and monoclonal antibody phenotype, as well as functional assays of the leukemic cells and will be compared with the variability observed between different normal leukocyte subpopulations. Key proteins that emerge from this comparison will be further characterized by HPLC. It is hoped that the proposed study will delineate characteristic protein patterns in acute leukemia that might be correlated with prognosis and response to treatment and that it would serve as a basis for similar studies of other proliferative disorders.